title: Concrete thawing studied by single-point ramped imaging.
abstract: A series of two-dimensional images of proton distribution in a hardened concrete sample has been obtained during the thawing process (from -50 degrees C up to 11 degrees C). The SPRITE sequence is optimal for this study given the characteristic short relaxation times of water in this porous media (T2* < 200 micros and T1 < 3.6 ms). The relaxation parameters of the sample were determined in order to optimize the time efficiency of the sequence, permitting a 4-scan 64 x 64 acquisition in under 3 min. The image acquisition is fast on the time scale of the temperature evolution of the specimen. The frozen water distribution is quantified through a position based study of the image contrast. A multiple point acquisition method is presented and the signal sensitivity improvement is discussed.
authors.affiliation: MRI Centre, Department of Physics, University of New Brunswick, Fredericton, Canada.
authors.forename: P J
authors.initials: PJ
authors.lastname: Prado
authors.forename: B J
authors.initials: BJ
authors.lastname: Balcom
authors.forename: S D
authors.initials: SD
authors.lastname: Beyea
authors.forename: R L
authors.initials: RL
authors.lastname: Armstrong
authors.forename: T W
authors.initials: TW
authors.lastname: Bremner
mesh_terms: D007091:Image Processing, Computer-Assisted / Q000379:methods; D008279:Magnetic Resonance Imaging / Q000379:methods*; D014867:Water / Q000032:analysis
chemical_list: D014867:Water